<body>
<script>
function myonclick(event) {
    alert('event.offsetX=' + event.offsetX + ',event.offsetY=' + event.offsetY);
    alert('event.clientX=' + event.clientX + ',event.clientY=' + event.clientY);
}
</script>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
<div style="border: solid red; padding: 20px; overflow: scroll; width: 200px; height: 100px;">
blah blah <a href="#" onclick="return myonclick(event);">link <i>with em text</i></a>
<br>
blah
<br>
blah
</div>

<div style="position: absolute; left: 100px; height: 100px; border: solid blue; width: 1px; height: 1px;"></div>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
blah<br>
</body>